The present invention relates to Electronic Stability Control systems for vehicles.
Electronic stability control (ESC) systems are a powerful safety addition to modern vehicles. ESC systems help drivers maintain control under compromising road conditions, challenging maneuvers and variations in driver responses or abilities. Many vehicle models being manufactured today have installed ESC systems as standard equipment. It is expected that ESC systems will become even more widely used in the future.
ESC systems are a computer-based technology that detects and reduces lateral vehicle skidding. An ESC system detects a loss of vehicle steering control and then applies appropriate braking individually at each wheel to help direct the vehicle in accordance with the driver's steering wheel input. More specifically, electronic stability control (ESC) systems operate by individually actuating the wheel brakes to induce a yaw moment on the car for the purpose of improving stability and performance. In order for the ESC system to accomplish this, the ESC system analyzes what the car is actually doing, and what the car “should” be doing under ideal circumstances.
Conventional ESC instrumentation includes a steering wheel position sensor, a lateral accelerometer, wheel speed sensors, a yaw rate sensor, sensors for brake and throttle inputs, and an enable/disable switch. The actuation is managed by an electronic control unit (ECU) and a hydraulic control unit (HCU). The ESC system can actuate wheel brake pressure as well as engine throttle to affect the dynamics of the car.
ESC system design tries to assist the driver without either taking control away from the driver or overriding the driver's “feel” of the road. It is a feature of ESC systems that the driver should be able to feel some slip of the tires to know when to self-modulate the speed or steering. When the ESC system does activate, the character of the driver's response does not change. The ESC system intervention makes the driver's inputs more effective.
Although existing ESC systems provide useful benefits and advantages, there continues to be room for improvements.